Abstract

Based on a newly developed TMAP-classification system, some important ecological developments in the Wadden Sea dunes can be distinguished. One of the most striking changes during the last decades is the increased share of mid-successional stages dominated by one or few highly competitive and productive species, mostly grasses. Regrettably this is countervailed by a decreasing space for pioneer stages which are generally characterized by a much higher biodiversity.
Such developments can partly be ascribed to human influences within the dunes, such as complexes of buildings, infrastructural elements, groundwater extractions, disturbing ativities, etc.. However many causes, probably more fundamental, can be found in events and patterns on or past the borders of dune areas. At the North Sea border sea defense management has a large influence on sand erosion and accretion regimes, which under natural circumstances determine regressional or successional change of biological communities in a large part of the dune area. At the opposite side natural, gradual transitions from dunes to saltmarshes and littoral and sublittoral sand flats are largely replaced by sharp borders with egalized and drained agricultural land, residence places or other anthropogenic elements. Especially the hydrological effects of such sharp boundaries may be influential over large distances in the adjacent dune area.
Administrative borders, such as between countries or management organizations, lead to differences in ecological development by differences in approaches and allowable threats. Exchanging knowledge and experiences may contribute to an optimization of managerial and political practices while maintaining the “innocent” differences across the borders.

>> Programm zum Download